諾麗果汁已是廣受消費者信賴的保健食品，但其果汁含有不良氣味的揮發性有機酸，為修飾這種令人不悅的氣味，通常諾麗果汁商品會摻配蔓越莓或葡萄等果汁調整風味。然而這種調配果汁所含的機能性成份便會被稀釋，保健功效相對降低。本研究旨在於利用酵母菌MRA6處理諾麗果汁，減少揮發性有機酸含量，改善風味，同時並能保留果汁原有機能性成份的含量。本研究採用自然發酵一個月製成的諾麗果汁。利用MRA6處理自然發酵的諾麗果汁，經過三天去除氣味後，使用UPLC檢測機能性成分，得知東莨菪素由258.29μg/mL減少至210.24μg/mL(約 19%)，其他成分如酚類化合物、類黃酮、芸香素則無顯著差異；並以GC分析，結果確認可去除果汁中不良氣味的成份如丁酸、二甲基丁酸、己酸、辛酸。酵母菌MRA6具有降解揮發性有機酸的能力，將可應用於諾麗果汁風味的改善。 Noni juice has been considered as health food in many countries. Fresh noni juice contains some volatile organic acids with unpleasant odor that put off consumer acceptance. Usually, the unpleasant odor was masked by blended grape juice, cranberry juice, or blueberry juice in manufacturing commercial noni juice products. In this kind of products, the amount of biofunctional compounds are inevitable decline. The aim of this study is to remove these volatile organic acids by using a yeast strain (MRA6), but not to reduce the level of biofunctional compounds. The noni juice used in this study was prepared by natural fermentation. The major biofunctional compounds such as phenolic compounds, flavonoids and rutin of the fermented juice were not reduced significantly after treating by MRA6. But another valuable biofunctional compounds, scopotletin was slightly decreased for three day treatment, as showed by data of UPLC analysis. Foul smell organic acids, butyric acid, DL-2-methylbutyric acid, hexanoic acid, and octanoic acid in the yeast treated juice were obviously reduced, according to data of GC analysis. The reduction of these organic acids refers to that application of MRA6 to eliminate the unpleasant odor of noni juice is feasible to improve the flavor of noni juice.
